28813991 has 2 divisors, whose sum is σ = 28813992. Its totient is φ = 28813990.

The previous prime is 28813979. The next prime is 28814003. The reversal of 28813991 is 19931882.

It is a balanced prime because it is at equal distance from previous prime (28813979) and next prime (28814003).

It is a cyclic number.

It is not a de Polignac number, because 28813991 - 2¹⁸ = 28551847 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (28813901) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14406995 + 14406996.

It is an arithmetic number, because the mean of its divisors is an integer number (14406996).

Almost surely, 2^28813991 is an apocalyptic number.

28813991 is a deficient number, since it is larger than the sum of its proper divisors (1).

28813991 is an equidigital number, since it uses as much as digits as its factorization.

28813991 is an evil number, because the sum of its binary digits is even.

The product of its digits is 31104, while the sum is 41.

The square root of 28813991 is about 5367.8665221855. The cubic root of 28813991 is about 306.5734011962.

The spelling of 28813991 in words is "twenty-eight million, eight hundred thirteen thousand, nine hundred ninety-one".